Corrosion rate of Zircaloy-4 in deoxidized deionized water at 80-120°C

To evaluate the dissolution rate of radionuclides from hull waste under geological disposal conditions, corrosion tests using a coupon type of Zircaloy-4 specimen were conducted in deoxidized deionized water at 80, 100 and 120°C by a hydrogen gas generation rate method. The corroded depth of Zircaloy was proportional to the cubic root of corrosion time at each temperature. The corrosion rate constants obtained in the present study fell on the same line on the Arrhenius plot as those at a higher temperature of around 300°C that had been obtained in material research for light water reactors. These results indicate that the corrosion mechanism of Zircaloy at 80-120°C is the same as that at the higher temperature and that an empirical corrosion rate model at the higher temperature may be applicable to a temperature below 100°C that is likely under geological disposal conditions. (author)